A method for removing diazepam from water using molecular sieve

Abstract

The present invention provides a method for removing diazepam from water using a molecular sieve, and belongs to the technical field of wastewater treatment. The method provided by the present invention comprises: mixing a molecular sieve with an aqueous solution containing diazepam, and then sequentially performing vortex adsorption, centrifugation and filtration to obtain a treated aqueous solution; the molecular sieve comprises one or more of an H-Beta molecular sieve, a NaY molecular sieve, a HY molecular sieve, an H-ZSM molecular sieve, an H-MOR molecular sieve and a USY molecular sieve. The present invention limits a specific molecular sieve as an adsorbent, and this type of molecular sieve has a strong polarity and can selectively adsorb diazepam from water. The results of the examples show that the present invention uses a USY molecular sieve as an adsorbent, and the adsorption time required to reach equilibrium is only 10 minutes, the adsorption time is short, and the adsorption amount is large, and it has good selectivity for diazepam.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for removing diazepam from water by utilizing molecular sieves. Background Art

[0002] Diazepam (DZP), a benzodiazepine, is widely used clinically to treat epileptic seizures, anxiety, insomnia, and convulsions. Benzodiazepines are widely present in various wastewaters and are stable in water due to their resistance to photodegradation. Studies have reported that long-term exposure to diazepam can negatively impact aquatic organisms, even at low residual concentrations.

[0003] With the increasing pollution problem of psychoactive drugs such as diazepam, domestic and foreign scholars have conducted research in many directions on its removal technology, including adsorption, ozone oxidation, microbial degradation, photocatalytic degradation and electrochemical oxidation. Compared with microbial degradation and electrochemical oxidation, adsorption is one of the most widely used technologies. For example, Chinese patent CN202010735988.1 discloses a solid phase extraction column for diazepam residue detection, which is used in the sample pretreatment process of diazepam residue detection. However, this method is complicated to operate, has low adsorption efficiency, and has a small wastewater treatment volume, making it difficult to apply to the removal of diazepam in large amounts of wastewater. Coslop used natural zeolite as an adsorbent to adsorb diazepam in water. The results showed that the adsorption equilibrium time of natural zeolite for diazepam in water was 350 minutes, and the maximum adsorption capacity was only 8.25 mg / g (Coslop, TF, Nippes, RP, Bergamasco, R., & Scaliante, MHNO (2022). Evaluation of diazepam adsorption inaqueous media using low-cost and natural zeolite: equilibrium and kinetics. Environmental Science and Pollution Research, 29(53), 79808-79815.). In addition, existing adsorbents have poor selectivity for diazepam in water.

[0004] It can be seen that the existing technology for removing diazepam from wastewater has problems such as low adsorption efficiency, slow adsorption rate and poor selectivity. Summary of the Invention

[0005] The object of the present invention is to provide a method for removing diazepam from water using molecular sieves. The method provided by the present invention can selectively adsorb diazepam, and has high adsorption efficiency and fast adsorption rate.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for removing diazepam from water using molecular sieves, comprising: mixing the molecular sieves with an aqueous solution containing diazepam, and then sequentially performing vortex adsorption, centrifugation, and filtration to obtain a treated aqueous solution;

[0008] The molecular sieve includes one or more of H-Beta molecular sieve, NaY molecular sieve, HY molecular sieve, H-ZSM molecular sieve, H-MOR molecular sieve and USY molecular sieve.

[0009] Preferably, the silicon to aluminum molar ratio of the molecular sieve is 1 to 80.

[0010] Preferably, the molecular sieve is prepared by hydrothermal synthesis.

[0011] Preferably, the initial concentration of the aqueous solution containing diazepam is 10 to 500 mg / L.

[0012] Preferably, the pH value of the aqueous solution containing diazepam is 1-12.

[0013] Preferably, the ionic strength of the aqueous solution containing diazepam is 0-60%.

[0014] Preferably, the ratio of the mass of the molecular sieve to the volume of the aqueous solution containing diazepam is (2-200) mg:(5-100) mL.

[0015] Preferably, the vortex rotation speed of the vortex adsorption is 1000-2500 r / min.

[0016] Preferably, the vortex adsorption time is 1 to 100 minutes.

[0017] Preferably, the centrifugal speed is 5000-12000 r / min.

[0018] The present invention provides a method for removing diazepam from water using molecular sieves, comprising: mixing the molecular sieve with an aqueous solution containing diazepam, and then sequentially performing vortex adsorption, centrifugation, and filtration to obtain a treated aqueous solution; the molecular sieves include one or more of H-Beta molecular sieves, NaY molecular sieves, HY molecular sieves, H-ZSM molecular sieves, H-MOR molecular sieves, and USY molecular sieves. The present invention defines a specific molecular sieve as an adsorbent, and this type of molecular sieve has a strong polarity and can selectively adsorb diazepam from water. The results of the examples show that the present invention uses USY molecular sieves as adsorbents, and the adsorption time required to reach equilibrium is only 10 minutes, which is a short adsorption time, and the adsorption amount at equilibrium reaches 120.7 mg / g, which is a large adsorption amount; the adsorption capacity for diazepam is stronger than the adsorption capacity for enrofloxacin and estazolam, indicating that the USY molecular sieve has good selectivity for diazepam. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a graph showing the effect of different adsorption times on the adsorption performance of diazepam according to the present invention;

[0020] Figure 2 Graph showing the effect of the initial concentration of the aqueous solution containing diazepam on the adsorption performance of the present invention;

[0021] Figure 3 This is the fitting result diagram of the adsorption process of the USY type molecular sieve of the present invention;

[0022] Figure 4 This is a fitting result diagram of the adsorption results of the molecular sieve of the present invention on aqueous solutions containing diazepam with different initial concentrations;

[0023] Figure 5 This is a graph showing the effect of the molecular sieve of the present invention on the selective adsorption performance of diazepam. DETAILED DESCRIPTION

[0024] The present invention provides a method for removing diazepam from water using molecular sieves, comprising: mixing the molecular sieves with an aqueous solution containing diazepam, and then sequentially performing vortex adsorption, centrifugation, and filtration to obtain a treated aqueous solution;

[0025] The molecular sieve includes one or more of H-Beta molecular sieve, NaY molecular sieve, HY molecular sieve, H-ZSM molecular sieve, H-MOR molecular sieve and USY molecular sieve.

[0026] The present invention mixes a molecular sieve with an aqueous solution containing diazepam, and then sequentially performs vortex adsorption, centrifugation and filtration to obtain a treated aqueous solution.

[0027] In the present invention, the molecular sieve includes one or more of H-Beta, NaY, HY, H-ZSM, H-MOR, and USY molecular sieves, with USY, HY, and H-ZSM molecular sieves being more preferred. The molecular sieves used in the present invention have strong polarity and can selectively adsorb diazepam in water.

[0028] In the present invention, the pore size of the H-Beta, NaY, HY, H-ZSM, H-MOR, and USY molecular sieves is preferably 0.2 nm to 10 nm, more preferably 0.3 nm to 5 nm. The present invention uses molecular sieves with the above pore sizes to selectively adsorb diazepam in water.

[0029] In the present invention, the silicon-aluminum molar ratio of the molecular sieve is preferably 1 to 80, more preferably 50 to 80. In the present invention, as the silicon-aluminum ratio of the feed increases, the actual silicon-aluminum ratio and the average particle size of the molecular sieve gradually increase, and the number of total pores and micropores decreases. The present invention controls the silicon-aluminum molar ratio within the above range, which is more conducive to controlling the pore structure of the molecular sieve, and further facilitates the selective adsorption of diazepam in water.

[0030] In the present invention, the preparation method of the molecular sieve is preferably a hydrothermal synthesis method.

[0031] In the present invention, the hydrothermal synthesis method of the molecular sieve preferably includes:

[0032] (1) mixing a silicon source, an aluminum source, a template, NaOH, and water and performing a hydrothermal reaction to obtain an intermediate;

[0033] (2) calcining the intermediate obtained in step (1) to obtain an intermediate molecular sieve;

[0034] (3) mixing the intermediate molecular sieve obtained in step (2) with an ammonium salt aqueous solution and performing ion exchange to obtain a molecular sieve.

[0035] In the present invention, the silicon source, the aluminum source, the template, NaOH and water are preferably mixed and then subjected to a hydrothermal reaction to obtain an intermediate.

[0036] In the present invention, the silicon source preferably includes silica sol, organic silicate, white carbon black or water glass; the aluminum source preferably includes sodium metaaluminate, aluminum sulfate, aluminum hydroxide or aluminum nitrate; the template preferably includes n-butylamine, tetraethoxyammonium hydroxide, tetrapropylammonium hydroxide or tetraethylammonium bromide. In the present invention, when the template is tetraethoxyammonium hydroxide, the molecular sieve obtained is an H-Beta molecular sieve; when the template is n-butylamine, the molecular sieve obtained is an HY molecular sieve; when the template is n-butylamine, the molecular sieve obtained is a NaY molecular sieve; when the template is tetraethylammonium bromide, the molecular sieve obtained is an H-ZSM molecular sieve; when the template is tetrapropyl sodium hydroxide, the molecular sieve obtained is an H-MOR molecular sieve.

[0037] In the present invention, the molar ratio of the silicon source, aluminum source, template and NaOH is preferably (1-100):(1-50):(0.01-1):(0.1-10), more preferably (1-60):(1-30):(0.02-0.8):(0.1-5).

[0038] The volume of water is not particularly limited in the present invention and can be adjusted as needed. In the present invention, the ratio of the amount of the silicon source to the volume of water is preferably (1-100) mmol: (100-400) mL, more preferably (1-60) mmol: (100-300) mL.

[0039] In the present invention, the temperature of the hydrothermal reaction is preferably 120-180°C, more preferably 150-160°C; the time of the hydrothermal reaction is preferably 8-48 hours, more preferably 12-24 hours. By controlling the temperature and time of the hydrothermal reaction within the above ranges, the present invention can achieve a more complete reaction.

[0040] In the present invention, the system after the hydrothermal reaction is preferably centrifuged, washed and dried in sequence to obtain an intermediate.

[0041] The present invention has no particular limitation on the rotation speed and time of the centrifugation, as long as the solids in the system can be fully settled.

[0042] In the present invention, the washing agent is preferably ultrapure water. By washing the solid obtained by centrifugation with ultrapure water, impurities on the solid surface can be removed. The present invention does not specifically limit the number of washes; the solid can be washed until the pH of the washing solution reaches 7 to 8.

[0043] In the present invention, the drying is preferably vacuum drying, and the vacuum drying temperature is preferably 60-120° C., more preferably 100-120° C. The present invention has no particular limitation on the vacuum drying time, and the time is adjusted according to the amount of solid to be dried, so as to fully dry the solid.

[0044] After obtaining the intermediate, the present invention preferably calcines the intermediate to obtain the intermediate molecular sieve.

[0045] In the present invention, the calcination temperature is preferably 500-600°C, more preferably 550°C; the calcination time is preferably 6-9 hours, more preferably 8 hours. By controlling the calcination temperature and time within the above ranges, the present invention is more conducive to fully removing the template.

[0046] After obtaining the intermediate molecular sieve, the present invention mixes the intermediate molecular sieve with an ammonium salt aqueous solution and performs ion exchange to obtain the molecular sieve.

[0047] In the present invention, the concentration of the ammonium salt aqueous solution is preferably 0.5 to 2 mol / L, more preferably 0.5 to 1.5 mol / L. In the present invention, the ratio of the mass of the intermediate molecular sieve to the volume of the ammonium salt aqueous solution is preferably (100 to 1000) mg: (20 to 80) mL, more preferably (300 to 800) mg: (40 to 60) mL. In the present invention, the ammonium salt preferably includes ammonium nitrate, ammonium sulfate, ammonium chloride or ammonium bromide.

[0048] In the present invention, the ion exchange temperature is preferably 80-100°C, more preferably 90-100°C; the ion exchange is preferably performed three times, and the duration of each exchange is preferably 2 hours. The present invention can obtain the desired molecular sieve by using an ammonium salt aqueous solution to perform ion exchange on the intermediate molecular sieve.

[0049] In the present invention, the system after ion exchange is preferably centrifuged, washed, dried and calcined in sequence to obtain a molecular sieve.

[0050] In the present invention, the operation methods and parameters of centrifugation, washing, drying and calcination are the same as those of the preparation of the intermediate molecular sieve, and will not be described in detail here.

[0051] In the present invention, the preparation method of the USY molecular sieve preferably comprises: mixing the NaY molecular sieve with an ammonium sulfate solution, performing ion exchange, and then sequentially filtering, washing, drying and steaming to obtain the USY molecular sieve.

[0052] In the present invention, the concentration of the ammonium sulfate solution is preferably 0.1 to 5 mol / L, more preferably 0.5 to 3 mol / L.

[0053] In the present invention, the temperature of the ion exchange is preferably 60-100° C., more preferably 80-90° C.; the time of the ion exchange is preferably 1-3 h, more preferably 2-3 h; and the ion exchange is preferably performed under stirring.

[0054] The present invention has no particular limitation on the drying temperature and time, as long as the water on the surface of the molecular sieve can be fully removed.

[0055] In the present invention, the temperature of the water vapor treatment is preferably 500-800°C, more preferably 600-700°C; the time of the water vapor treatment is preferably 1-4 hours, more preferably 2-3 hours; the volume percentage of the water vapor is preferably 60-120%, more preferably 80-100%. In the present invention, the NaY type molecular sieve is ion exchanged in the atmosphere of ammonium ion aqueous solution to become the NH4Y type molecular sieve. The high temperature water vapor enters the interior of the NH4Y type molecular sieve, and the framework aluminum and silicon react easily with the high temperature water vapor to generate Al(OH) x and Si(OH)4, but Si(OH)4 is unstable, and part of it enters the vacancies generated by dealumination and dehydrates with the skeleton hydroxyl groups; therefore, the present invention can achieve the purpose of dealumination and silicon supplementation through water vapor treatment.

[0056] The hydrothermal method provided by the present invention is simple to operate, and the prepared molecular sieve has a relatively suitable pore size and polarity, which is more conducive to improving the selective adsorption of diazepam in water.

[0057] In the present invention, the initial concentration of the aqueous solution containing diazepam is preferably 10 to 500 mg / L, more preferably 20 to 300 mg / L. When the initial concentration of the aqueous solution containing diazepam is controlled within the above range, the molecular sieve is more conducive to the adsorption of diazepam.

[0058] In the present invention, the pH value of the aqueous solution containing diazepam is preferably 1 to 12, more preferably 5 to 8. In the present invention, the pKa of diazepam is 3.7. A pH value that is too low will cause diazepam to be protonated, and a pH value greater than 8 will cause partial hydrolysis of diazepam. In the present invention, controlling the pH value of the aqueous solution containing diazepam within the above range can prevent the pH value from being too low, which is not conducive to the adsorption of diazepam by the molecular sieve, and can also prevent the pH value from being too high, which leads to poor adsorption effect.

[0059] In the present invention, the ionic strength of the aqueous solution containing diazepam is preferably 0-60%, more preferably 0-30%. In the present invention, controlling the ionic strength of the aqueous solution containing diazepam within the above range is more conducive to improving the adsorption capacity of the molecular sieve for diazepam.

[0060] In the present invention, the ratio of the mass of the molecular sieve to the volume of the aqueous solution containing diazepam is preferably (2-200) mg:(5-100) mL, more preferably (10-100) mg:(50-80) mL. Controlling the ratio of the mass of the molecular sieve to the volume of the aqueous solution containing diazepam within the above range is more conducive to fully adsorbing diazepam in water.

[0061] The present invention has no particular limitation on the method of mixing the molecular sieve and the aqueous solution containing diazepam, and the two can be placed in the same container.

[0062] In the present invention, the vortex adsorption speed is preferably 1000-2500 r / min, more preferably 1500-2000 r / min; the vortex adsorption time is preferably 1-100 min, more preferably 2-60 min. By controlling the vortex adsorption speed and time within the above ranges, the present invention is more conducive to promoting the adsorption of diazepam by the molecular sieve.

[0063] In the present invention, the centrifugal speed is preferably 5000 to 12000 r / min, more preferably 5000 to 10000 r / min. The centrifugation of the present invention can settle the molecular sieve to the bottom and separate it from the aqueous solution. The centrifugation time is not particularly limited and can be adjusted as needed to allow the molecular sieve to fully settle.

[0064] In the present invention, the pore size of the filter paper is preferably 0.2 to 0.45 μm, more preferably 0.22 μm. The present invention can remove residual solid impurities in the aqueous solution by filtration, thereby reducing the content of solid impurities in the treated aqueous solution.

[0065] The method provided by the present invention is simple to operate, and by limiting a specific molecular sieve as an adsorbent, the molecular sieve has strong polarity and a suitable pore size and can selectively adsorb diazepam from water.

[0066] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0067] Example 1

[0068] A method for removing diazepam from water using molecular sieves:

[0069] 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 40 minutes; then centrifuged at a speed of 5000 r / min, and the supernatant was collected and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0070] Wherein: the concentration of the aqueous solution containing diazepam is 80 mg / L, the pH value is 6, and the ionic strength is 5%;

[0071] The ratio of the mass of USY molecular sieve to the volume of the aqueous solution containing diazepam is 30 mg:50 mL;

[0072] The preparation method of USY molecular sieve is:

[0073] (1) A silicon source (tetraethyl orthosilicate), an aluminum source (aluminum nitrate), a template (n-butylamine), NaOH, and water were mixed and subjected to a hydrothermal reaction at 150° C. for 72 h. The mixture was cooled to room temperature, centrifuged and the supernatant was discarded. The product was washed with ultrapure water until the pH was 7-8, and vacuum dried at 100° C. to obtain an intermediate. The molar ratio of the silicon source, the aluminum source, the template, and NaOH was 60:1:0.05:0.5, and the volume ratio of the silicon source to water was 60 mmol:200 mL.

[0074] (2) calcining the intermediate obtained in step (1) at 550° C. for 8 h to remove the template to obtain a NaY-type intermediate molecular sieve;

[0075] (3) mixing the NaY intermediate molecular sieve obtained in step (2) with an ammonium salt aqueous solution (ammonium sulfate aqueous solution) having a concentration of 1 mol / L, performing ion exchange three times at 90° C., each exchange for 2 h, centrifuging and discarding the supernatant, washing until neutral, vacuum drying, and treating the product at 600° C. under saturated water vapor conditions for 2 h to obtain a USY molecular sieve; wherein the ratio of the mass of the NaY intermediate molecular sieve to the volume of the ammonium salt aqueous solution is 2 g:40 mL; and the silicon-aluminum molar ratio of the USY molecular sieve is 50.

[0076] Test Example 1

[0077] The diazepam content of the treated aqueous solution obtained in Example 1 was detected by high performance liquid chromatography-tandem mass spectrometry. The adsorption performance of the USY molecular sieve for diazepam is reflected by the adsorption amount Q. The calculation method of the Q value is shown in formula (1):

[0078]

[0079] In formula (1), C0 is the initial concentration of the adsorption solution, in mg / L;

[0080] C t is the concentration of the supernatant after adsorption, in mg / L;

[0081] V is the volume of the adsorption liquid, in L;

[0082] M is the mass of the adsorbent in g.

[0083] According to the test, the adsorption capacity Q of diazepam by the USY molecular sieve in this embodiment is 59.10 mg / g.

[0084] Example 2

[0085] A method for removing diazepam from water using molecular sieves:

[0086] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 1 min; then, it was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0087] Example 3

[0088] A method for removing diazepam from water using molecular sieves:

[0089] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 2 minutes; then centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0090] Example 4

[0091] A method for removing diazepam from water using molecular sieves:

[0092] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 3 minutes; then centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0093] Example 5

[0094] A method for removing diazepam from water using molecular sieves:

[0095] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 5 minutes; then centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0096] Example 6

[0097] A method for removing diazepam from water using molecular sieves:

[0098] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 7 minutes; then centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0099] Example 7

[0100] A method for removing diazepam from water using molecular sieves:

[0101] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, it was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0102] Example 8

[0103] A method for removing diazepam from water using molecular sieves:

[0104] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 15 minutes; then centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0105] Example 9

[0106] A method for removing diazepam from water using molecular sieves:

[0107] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 20 min; then centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0108] Test Example 2

[0109] The treated aqueous solutions obtained in Examples 2 to 9 were tested using the method of Test Example 1, and the results of the effect of adsorption time on diazepam adsorption performance were obtained as shown in the figure below. Figure 1 As shown. Figure 1It can be seen that for a fixed amount of diazepam standard solution and a fixed amount of USY molecular sieve material, the adsorption capacity increases with adsorption time. After a certain adsorption time, the adsorption capacity reaches equilibrium because the sites on the molecular sieve adsorbent are completely occupied by diazepam. The adsorption time required to reach equilibrium is only 10 minutes, which is short, and the adsorption capacity at equilibrium reaches 83.46 mg / g.

[0110] Example 10

[0111] A method for removing diazepam from water using molecular sieves:

[0112] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 20 mg / mL, and vortex adsorption was performed at a speed of 2000 r / min for 10 min; then, centrifugation was performed at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0113] Example 11

[0114] A method for removing diazepam from water using molecular sieves:

[0115] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 40 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, it was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0116] Example 12

[0117] A method for removing diazepam from water using molecular sieves:

[0118] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 60 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, it was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0119] Example 13

[0120] A method for removing diazepam from water using molecular sieves:

[0121] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 80 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, it was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0122] Example 14

[0123] A method for removing diazepam from water using molecular sieves:

[0124] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 100 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, the mixture was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0125] Example 15

[0126] A method for removing diazepam from water using molecular sieves:

[0127] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 150 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, it was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0128] Example 16

[0129] A method for removing diazepam from water using molecular sieves:

[0130] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 200 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, the mixture was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0131] Example 17

[0132] A method for removing diazepam from water using molecular sieves:

[0133] The difference from Example 1 is that: 30 mg of USY molecular sieve was mixed with 50 mL of an aqueous solution containing diazepam at a concentration of 300 mg / mL, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then, the mixture was centrifuged at a speed of 5000 r / min, and the supernatant was taken and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0134] Test Example 3

[0135] The treated aqueous solutions obtained in Examples 10 to 17 were tested using the method of Test Example 1, and the effect of initial concentration on diazepam adsorption performance was obtained. Figure 2 As shown. Figure 2 It can be seen that for a fixed amount of USY molecular sieve material, the adsorption amount gradually increases with the increase of the adsorption liquid concentration. When a certain concentration is reached, the adsorption amount reaches equilibrium, and the adsorption amount at equilibrium reaches 120.7 mg / g.

[0136] Test Example 4

[0137] (1) The pseudo first-order kinetics and pseudo second-order kinetics equations were used to fit the adsorption process of USY molecular sieves to explore the factors that mainly affect the adsorption rate of molecular sieves. The fitting results are shown in Figure 3 As shown, the results are more consistent with the pseudo-second-order kinetic model, indicating that the adsorption of diazepam by USY type molecular sieve is mainly controlled by the chemical adsorption mechanism.

[0138] (2) The Langmuir isotherm adsorption model and the Freundlich isotherm adsorption model were used to fit the initial concentration optimization data of the adsorption solution. The fitting results are shown in Figure 4 The results showed that the adsorption of diazepam by molecular sieve was more consistent with the Langmuir isotherm adsorption model, indicating that it was a monolayer adsorption process.

[0139] Example 18

[0140] A method for removing diazepam from water using molecular sieves:

[0141] The difference from Example 1 is that:

[0142] The difference from Example 1 is that 30 mg of USY molecular sieves were mixed with 50 mL of an aqueous solution containing diazepam, and the mixture was vortexed and adsorbed at a speed of 2000 r / min for 10 min; then centrifuged at a speed of 5000 r / min, and the supernatant was collected and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution;

[0143] The concentrations of diazepam, enrofloxacin, and estazolam in the aqueous solution containing diazepam are each 80 mg / L.

[0144] Test Example 5

[0145] The treated aqueous solution obtained in Example 18 was tested using the method of Test Example 1, and the effect of molecular sieves on the selective adsorption performance of diazepam was obtained as shown in the figure below: Figure 5 As shown. Figure 5 It can be seen that the adsorption capacity of USY type molecular sieve for diazepam is stronger than that for enrofloxacin and estazolam, indicating that USY type molecular sieve has good selectivity for diazepam.

[0146] Example 19

[0147] A method for removing diazepam from water using molecular sieves:

[0148] The preparation method of the aqueous solution containing diazepam is as follows: the aquaculture pond water is allowed to stand for sedimentation, the upper layer is centrifuged at 12,000 rpm for 10 minutes for further separation, and then filtered through a 0.22 μm filter membrane to further remove impurities. Different concentrations of diazepam standard solution are added to the aquaculture pond water and paddy water to prepare aqueous solutions of 0.04 mg / L and 0.40 mg / L, respectively.

[0149] 30 mg of USY molecular sieves were mixed with 50 mL of the above-mentioned 0.04 mg / L aqueous solution containing diazepam, and vortexed at a speed of 2000 r / min for 10 min; then centrifuged at a speed of 5000 r / min, and the supernatant was collected and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution;

[0150] 30 mg of USY molecular sieves were mixed with 50 mL of the above-mentioned 0.40 mg / L aqueous solution containing diazepam, and vortex adsorption was performed at a rotation speed of 2000 r / min for 10 minutes; then centrifugation was performed at a rotation speed of 5000 r / min, and the supernatant was collected and filtered through a 0.22 μm nylon membrane to obtain a treated aqueous solution.

[0151] Example 20

[0152] The difference from Example 19 is that paddy field water is used instead of aquaculture pond water, and the remaining steps are the same as Example 19.

[0153] Test Example 6

[0154] The treated aqueous solutions obtained in Examples 19 and 20 were subjected to high performance liquid chromatography-tandem mass spectrometry, respectively, with three replicate measurements at each level. The results of the spiked recovery tests for diazepam in aquaculture pond water and paddy field water are shown in Table 1:

[0155] Table 1 Results of spiked recovery tests in aquaculture pond water and paddy field water

[0156]

[0157] As can be seen from Table 1, when the diazepam addition levels in aquaculture pond water and rice field water were 0.04 mg / L and 0.40 mg / L, respectively, the average recoveries were 92.8-101.8%, and the RSDs were 0.49-2.89%, indicating that the method provided by the present invention has high accuracy and precision for detecting diazepam in actual water samples.

[0158] From the above experimental results, it can be seen that the molecular sieve used in the present invention can selectively adsorb diazepam in water with high adsorption efficiency and fast adsorption rate, which solves the problems of poor selectivity, low adsorption efficiency and slow adsorption rate in the prior art when removing diazepam.

[0159] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for removing diazepam from water using molecular sieves, comprising: After mixing the molecular sieve with the aqueous solution containing diazepam, vortex adsorption, centrifugation and filtration are carried out in sequence to obtain a treated aqueous solution; The molecular sieve includes one or more of H-Beta molecular sieve, NaY molecular sieve, HY molecular sieve, H-ZSM molecular sieve, H-MOR molecular sieve and USY molecular sieve.

2. The method for removing diazepam from water using molecular sieve according to claim 1, characterized in that: The silicon-aluminum molar ratio of the molecular sieve is 1-80.

3. The method for removing diazepam from water using molecular sieves according to claim 1 or 2, characterized in that: The preparation method of the molecular sieve is a hydrothermal synthesis method.

4. The method for removing diazepam from water using molecular sieves according to claim 1, characterized in that: The initial concentration of the aqueous solution containing diazepam is 10 to 500 mg / L.

5. The method for removing diazepam from water using molecular sieves according to claim 4, characterized in that: The pH value of the aqueous solution containing diazepam is 1-12.

6. The method for removing diazepam from water using molecular sieves according to claim 4, characterized in that: The ionic strength of the aqueous solution containing diazepam is 0-60%.

7. The method for removing diazepam from water using molecular sieves according to claim 1 or 4, characterized in that: The ratio of the mass of the molecular sieve to the volume of the aqueous solution containing diazepam is (2-200) mg:(5-100) mL.

8. The method for removing diazepam from water using molecular sieves according to claim 1, characterized in that: The vortex rotation speed of the vortex adsorption is 1000-2500 r / min.

9. The method for removing diazepam from water using molecular sieves according to claim 8, characterized in that: The vortex adsorption time is 1 to 100 minutes.

10. The method for removing diazepam from water using molecular sieves according to claim 1, characterized in that: The centrifugal speed is 5000-12000 r / min.

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